This invention relates to ball injecting apparatus for use in earth wells. In the completion of oil and gas wells, it is common practice to cement casing into the well and perforate it opposite the producing formation, such perforations being for the purpose of admitting oil and/or gas into the casing and thence to the surface of the well.
Subsequent to perforating the casing, the formation may be treated by pumping acid or fracturing fluid down the casing and into the formation via the perforations. Such treatment opens and/or enlarges drainage channels in the formation so as to enhance the producing ability of the well.
As is well-known to those skilled in the art, the treating fluid enters those zones of the formation having the highest permeability while the zones of the formation having lower permeabilities, and therefore requiring treatment the most, receive very little or none. The remedy to this problem was disclosed in U.S. Pat. No. 2,754,910 wherein it was proposed to temporarily block off those perforations leading to the higher permeable zones so as to divert the treating fluid into the lower permeable zones. The blocking agents used are objects having a size slightly larger than the perforations and a density approximately equal to the treating fluid. These objects which may be rounded and referred to as balls, are dispensed into the treating fluid and carried thereby to the perforations through which most or all of the fluid flows at the lowest pressure. The fluid pressure holds the objects or balls in sealing position against the perforations so that the treating fluid is diverted into the lower permeable zones.
Workers have attempted to develop dispensers capable of being employed in high pressure environments and where the treating fluid is heavily laden with abrasive such as sand, glass beads, and the like. Further problems acknowledged by those skilled in the art include unintentionally dispensing more than the desired number of balls and a lack of a reliable mechanical means of forcing the balls into the flow stream.
One ball injector device which is reasonably satisfactory in alleviating the above-mentioned problems is described and claimed in U.S. Pat. No. 3,715,055.